Operating instructions

R&S ESCI More Complex Programming Examples
1166.6004.12 7.21 E-1
Shape Factor Measurement (using n dB down)
The n-dB-down function of the R&S ESCI is used twice to determine the shape factor of a filter (ratio of
bandwidths at 60 dB and 3 dB below the filter maximum).
The following example is again based on a signal with a level of –30 dBm at 100 MHz. The shape factor
is determined for the 30 kHz resolution bandwidth. The default setting of the R&S ESCI is used for
measurements (SetupInstrument).
REM ************************************************************************
Public Sub ShapeFactor()
result$ = Space$(100)
'--------- R&S ESCI default setting ----------------------------------------
-
CALL SetupInstrument 'Default setting
CALL IBWRT(receiver%,"INIT:CONT OFF") 'Single sweep
'--------- Set frequency ---------------------------------------------------
CALL IBWRT(receiver%,"FREQ:SPAN 1MHz") 'Span
CALL IBWRT(receiver%,"BAND:RES 30kHz") 'Resolution bandwidth
CALL IBWRT(receiver%,"INIT;*WAI") 'Perform sweep with sync
'--------- Measure 60 dB value ---------------------------------------------
CALL IBWRT(receiver%,"CALC:MARK:PEXC 6DB") 'Peak excursion
CALL IBWRT(receiver%,"CALC:MARK:STAT ON") 'Marker1 on
CALL IBWRT(receiver%,"CALC:MARK:TRAC 1") 'Assign marker1 to trace1
CALL IBWRT(receiver%,"CALC:MARK:MAX") 'Set marker1 to 100 MHz
CALL IBWRT(receiver%,"CALC:MARK:FUNC:NDBD 60dB")'Read out bandwidth measured
CALL IBWRT(receiver%,"CALC:MARK:FUNC:NDBD:RES?")'at 60 dB
CALL IBRD(receiver%,result$)
result60 = Val(result$)
'--------- Measure 3 dB Down value ----------------------------------------
CALL IBWRT(receiver%,"CALC:MARK:FUNC:NDBD 3dB")'Read out bandwidth measured
CALL IBWRT(receiver%,"CALC:MARK:FUNC:NDBD:RES?")'at 60 dB
CALL IBRD(receiver%,result$)
result3 = Val(result$)
'--------- Read out shape factor--------------------------------------------
Print "Shapefaktor 60dB/3dB: ";result60/result3
END SUB
REM
************************************************************************